1. Field of the Invention
The present invention relates to a slide fastener with an emergency or quick opening facility.
2. Description of the Related Art
It is known to modify a zip fastener construction so that the fastener can be opened without recourse to the slider. This has been achieved by omitting elements from a length of the fastener chain, on one or both tapes, such as shown in GB-A-678,755, GB-A-1480176 and GB-A-1514296 for example.
To prevent inadvertent opening of the fastener the sides may be reinforced to reduce flexibility at the omitted element as in GB-A-1480176 and GB-A-1514296. In GB-A-678755 a breakable connection bridges the tapes. U.S. Pat. No. 3,122,808 shows a quick release fastener using a clip.
We are particularly interested in providing a zip fastener with an emergency or quick release opening for use with an automobile air bag assembly. WO00/35719 shows a fastener using mushroom type engaging elements and a breakable sleeve for use with an air bag.
Side air bags in automobiles are typically housed in the seat back. On inflation, the bag bursts through an opening in the seat cover. This opening may be provided by a stitched seam, the stitching breaking. In another system plastic strips are sewn to the seat fabric and coupled to the air bag container. When the air bag inflates the air bag container opens, allowing the strips to separate.
With a stitched seam, inspection of the air bag assembly is difficult, as the seam must be re-sewn. With the plastic strips the assembly is complex and relatively expensive.
Accordingly, an object of our invention is to provide a zip fastener with a quick release or emergency release facility provided by modification of the fastener elements. At least one of the fastener elements is modified to facilitate disengagement of the coupled elements under the force of the expanding air bag. Typically two or more adjacent elements will be modified.
When used in a vehicle seat cover, the fastener should withstand forces tending to open the fastener in normal use, such as tension in the plane of the fastener, particularly tension applied across the line of the coupled elements. Thus, another object of our invention is to provide a modified fastener element which resists separation of the fastener under these conditions.
The fastener may also be subject to out of plane movement, for example by a person or child pressing the fastener inwards, into the seat. Thus, yet another object of our invention is to provide a modified fastener element which resists separation of the coupled elements when pressed in one direction transverse to the fastener plane, but allows separation when pressed in the opposite direction.
We particularly prefer to use a zip fastener having moulded plastics elements. The moulded plastics elements in standard form have a body which is moulded onto an edge of the fastener tape, a neck extending from the body and a head on the outer end of the neck. The neck forms a narrow or waisted region between the head and body.
The head of a fastener element fits between the necks of two adjacent elements on the opposite fastener tape to prevent separation of the coupled elements.
A shoulder is provided adjacent the element neck and cooperates with a groove in the head of an opposed element to limit out of plane movement of the fastener heads.